It catches up. Diagnosed at 19, wasn't prescribed the right neds til 26. It's a ticking time bomb for some

It can definitely take a long time for anyone to notice. A lot of people tend to subconsciously hide their symptoms as well, especially as kids to try and 'fit in' better. Plus, parents/guardians are usually there to help us or push us to do what we need to. As adults though, we're more on our own and we have more responsibility which is when things can start to feel a lot more overwhelming and we may struggle more which can be why we start noticing symptoms later on. (Plus, I'd say all kids are pretty weird and hyperactive so a lot of times it can just be written off as being a kid instead of having adhd, but I don't know lol)

I wasn't diagnosed until last year at 52. It has only been relatively recently that studies on ADHD have broadened past the "badly behaved little boy" idea.